The present invention relates to dampers in general, and more particularly to improvements in torsional vibration dampers which can be utilized in the power trains of motor vehicles, for example, to at least partially absorb shocks between the rotary output element of a prime mover (such as the camshaft or crankshaft of an internal combustion engine) and the housing of a friction clutch which is engageable to transmit torque to the rotary input element of a change-speed transmission. Still more particularly, the invention relates to improvements in torsional vibration dampers wherein an input member and an output member are rotatable with each other about a common axis as well as relative to each other against the opposition of one or more energy storing devices.
Commonly owned U.S. Pat. No. 5,377,796 (granted Jan. 3, 1995 to Oswald Friedmann et al. for "APPARATUS FOR TRANSMITTING FORCE BETWEEN ROTARY DRIVING AND DRIVEN UNITS") discloses a hydrokinetic torque converter wherein a torsional vibration damper is installed in a composite flywheel, namely between a primary flywheel which receives torque from the crankshaft or camshaft of an internal combustion engine and a secondary flywheel which drives the housing and the pump of the torque converter. The damper comprises a rotary input member which includes or is driven by the primary flywheel, a rotary output member which includes or drives the secondary flywheel, and an energy storing device which opposes rotation of the input and output members relative to each other. The energy storing device comprises at least two coil springs one of which is confined in the other. The length of the one coil spring matches or approximates that of the other coil spring.
U.S. Pat. No. 5,367,919 discloses a similar torsional vibration damping apparatus which also comprises coaxial primary and secondary flywheels and an energy storing device serving to oppose rotation of the flywheels relative to each other. The secondary flywheel can be coupled to the input shaft of a change-speed transmission by an engageable and disengageable friction clutch. The two flywheels carry spring-engaging portions which cause the energy storing device to store energy, or to store additional energy, when the two flywheels are caused to turn relative to each other.
The disclosure of each patent application and/or patent identified in this specification is incorporated herein by reference. This includes our German priority application Serial No. 198 09 894.4 filed Mar. 7, 1998.
A drawback of many presently known torsional vibration dampers is that they are too bulky, too expensive and/or insufficiently versatile. Moreover, the springs (such as coil springs) of energy storing devices in such conventional torsional vibration dampers are not, or cannot be, used to capacity under all circumstances of use which arise in the power train of a motor vehicle or in other fields in which the utilization of one or more torsional vibration damping apparatus is advisable or necessary.